Abstract: The present study evaluated rats’ performances on an olfactory match-to-sample task. Four rats
were trained on an identity match-to-sample (MTS) procedure, with common household spices
mixed with sterilized play sand used as stimuli. Digging in a sample cup filled with sand that
was mixed with a predetermined spice initiated the presentation of two comparison cups.
Digging in the comparison cup that contained the same scent as the sample cup was reinforced
by a sucrose pellet. After such training, novel olfactory stimuli were added to test for
generalized matching. All four rats developed high levels of matching accuracy and were able to
maintain performances that were well above chance with up to 37 stimuli. Three of the four rats
showed above chance accuracy on novel probe stimuli. Finally, two of the subjects were tested
on trials with three comparison stimuli, and both performed at above chance levels of accuracy
under these conditions. The use of olfactory stimuli as well as a multiple-exemplar approach
may have played a role in the demonstration of generalized identity matching-to-sample in the
present study.